當 need, want, require, worth(形容詞)后面接doing也可以表示被動。
Your hair wants cutting. 你的頭發(fā)該理了。
The floor requires washing. 地板需要沖洗。
The book is worth reading. 這本書值得一讀。
典型例題
The library needs___, but it'll have to wait until Sunday.
A. cleaning B. be cleaned C. clean D. being cleaned
答案A. need (實意) +n /to do, need (情態(tài))+ do，當為被動語態(tài)時，還可need + doing. 本題考最后一種用法，選A。如有to be clean 則也為正確答案。
典：done，"不可能已經(jīng)"。must not do 不可以(用于一般現(xiàn)在時)。
